Question

The IUPAC name of compoud (a) \(1,2,3\)-tricyanopropane (b) Propane-1, 2,3 -tricarbonitrile (c) 3 -cyanopentane- 1,5 -dinitrile (d) Propane-1, 2,3 -trinitrile.

Short answer

Option (b) 'Propane-1,2,3-tricarbonitrile' is the correct IUPAC name for the compound.

Step-by-step solution

Identifying the Nitrile Group

In organic chemistry, a nitrile is represented by the group itrile (-CN). The compound has trinitrile, which translates to three nitrile groups more than it needs in the structure.

Analyzing the Hydrocarbon Backbone

The base name 'propane' refers to a three-carbon alkane chain. Thus, the structure of the compound will be centered around a 3-carbon chain.

Compiling the IUPAC Name

According to IUPAC naming convention, when multiple identical groups (like the nitrile groups in this case) are attached, 'trinitrile' is used to describe the total of 3 groups. When three cyano groups (-CN) are present on a propane, each carbon in the propane will have one cyano group.

Matching the Options

From the options provided, the correct IUPAC name should correctly represent the location and existence of the cyano groups in the compound. 'Propane-1,2,3-tricarbonitrile' consistently describes the structure: each cyano group is placed on the respective carbon of the propane chain.

Key concepts

Nitrile Group

A nitrile group is a functional group in organic chemistry characterized by a carbon triple-bonded to a nitrogen atom, represented as (-C≡N) or simply -CN. This group is pivotal in determining the chemical behavior of a compound due to its electronegativity and unique bonding. Here are some key characteristics of the nitrile group:

• Stability: The strong carbon-nitrogen triple bond makes nitrile groups quite stable.
• Solubility: Nitriles can be soluble in water due to possible dipole interactions, but their solubility is generally dependent on the rest of the molecule.
• Reactivity: While stable, the nitrile group can undergo hydrolysis to form carboxylic acids under acidic or basic conditions.

Understanding how a nitrile behaves can assist in predicting the chemical characteristics of a compound it is part of.

Hydrocarbon Backbone

The hydrocarbon backbone refers to the chain of carbon atoms that forms the 'skeleton' of an organic molecule. In the context of naming and structure, it is critical to identify this backbone first. For example, in the compound 'Propane-1,2,3-tricarbonitrile', the hydrocarbon backbone is 'propane'.

• Carbon Chains: Hydrocarbon backbones can be linear or branched, affecting the compound's properties and naming.
• Length of the Backbone: Determines the base name in IUPAC nomenclature (e.g., methane, ethane, propane).
• Saturation: Hydrocarbon backbones can be saturated (alkanes) or unsaturated (alkenes, alkynes), influencing reactivity.

Recognizing the correct hydrocarbon backbone is essential in drawing the structure and naming the compound accurately.

Cyano Groups

Cyano groups refer to the nitrile group when it is considered as a substituent in a compound. In systematic naming, a cyano group is added to each relevant carbon position of the backbone. For instance, in propane, if there are three cyano groups, each group is attached to a different carbon in the chain.

• Numbering Positions: In 'Propane-1,2,3-tricarbonitrile', each cyano group is at a specific position marked by numbers.
• Count and Placement: If multiple cyano groups are present, prefixes like 'di-', 'tri-', 'tetra-' are used, with numerals indicating locations.
• Functionality: Adding more cyano groups can change the compound's properties significantly, such as boiling point and solubility.

Correctly identifying and positioning cyano groups aids in constructing the molecule as per its IUPAC nomenclature.

Organic Chemistry Naming

Organic chemistry naming, specifically IUPAC nomenclature, is a systematic way to name organic chemical compounds. This ensures that each compound has a unique and descriptive name based on its structure. Here’s how it generally works:

• Identifying the Longest Chain: Determines the main part of the name; this involves recognizing the main backbone of the molecule.
• Locants and Substituents: Numbers are used to specify the position of each substituent or functional group along the chain.
• Multiplicity: When identical groups are present, prefixes (di-, tri-, tetra-) indicate their number. For instance, 'tricarbonitrile' states there are three nitrile (cyano) groups.

By applying these rules, one can consistently name even complex organic molecules in a way that reveals their structure and functional groups clearly.